A typical method for driving a backlight of a display screen not only includes turning on a light emitting diode (LED) lamp but also includes other ways, such as local dimming, three-dimensional (3D) scanning, and the like. A microcontroller (MCU) is usually arranged in the display screen to process data. However, the MCU only drives the LED lamp and makes a plurality of LED lamps simultaneously turn on/off and control a power chip to work according to a constant frequency. Thus, an output power of a direct current (DC)-DC voltage converter is not in relation with multi-channels dimming frequency, and the power chip is not affected in real time. In low brightness conditions, the power chip works in the constant frequency, a power loss of the backlight driving circuit is same as a power loss in high brightness conditions.